Recent dramatic innovation on lithographic patterning techniques in the manufacture of semiconductor devices has made lithographic line widths finer and finer. In lithographic exposure, i line and g line were initially used, but they gave patterns with broad line widths, and the manufactured semiconductor devices thereby had low capacities. However, recent technological developments have allowed the use of KrF excimer laser to give patterns with dramatically finer line widths. Thereafter the technological developments have continued so as to adopt ArF excimer laser having a further shorter wavelength to lithographic exposure, and this has been achieved in very recent years. Customary resins, i.e., novolak or styrenic resins, have been used in exposure to KrF excimer laser beams. However, for exposure to ArF excimer laser beams, the novolak or styrenic resins have been replaced with resins containing no aromatic moieties, i.e., replaced with alicyclic resins, because the ArF excimer laser beams have a further shorter wavelength of 193 nm, and resins containing aromatic moieties, such as the novolak or styrenic resins, absorb the light of this wavelength. Such resins for photoresists require the property of being alkali-soluble as a result of the leaving of a moiety thereof with an acid and require uniform adhesion to the substrate. For satisfying these requirements, various polar groups are introduced into alicyclic resins. The resulting resins, however, tend to be slightly soluble in organic solvents for photoresists, probably because of their complicated structures.
Solutions as photoresist compositions should be subjected to fine or microscopic filtration before used in semiconductor manufacture, but most of them show poor filtration performance (filterability). To solve this problem, some techniques have been proposed as in Patent Literature (PTL) 1 and PTL 2. However, the lithographic techniques using ArF excimer laser are experiencing further evolution and currently employ immersion lithographic techniques which proceed and enable further finer patterning. This requires further improvements in filtration performance of resin solutions for photoresists.    PTL 1: Japanese Unexamined Patent Application Publication (JP-A) No. 2001-183837    PTL 2: Japanese Unexamined Patent Application Publication (JP-A) No. 2000-231200